A special committee examining changes to how Boston assigns students to schools is expected to vote on its recommendations Monday night, potentially ushering in the most dramatic overhaul in more than two decades.

The 27 members of the External Advisory Committee — following a year of public outreach, research, and deliberations — will recommend one of four student assignment proposals, each of which aims to let more students attend schools closer to their homes.

The winning proposal must receive a simple majority vote. But reaching that point is likely to involve considerable debate, and the meeting could last several hours, said Helen Dajer, the committee’s cochairwoman.

“I think we are headed in the right direction,” Dajer said. “Change is due. We need a new assignment system.”

If the advisory committee approves a proposal, Superintendent Carol R. Johnson could present the recommendations to the School Committee as soon as Wednesday night, kicking off another round of deliberations.

The School Committee has final say on any changes to student assignment, and it is unclear when its members will vote.

But some observers believe the advisory committee is voting on the proposals prematurely. They say a more comprehensive plan to overhaul lackluster schools needs to be developed first so all children can receive a strong education.

“How you assign seats doesn’t matter if there are not enough quality seats for everyone.”

Sai Samant, Member of Quest, a grass-roots parents’ group

“The advisory committee is pushing the school district to come up with some quality and academic interventions, but right now what I see [being proposed] is very vague,” said Kim Janey of Massachusetts Advocates for Children, a Boston nonprofit.

Mayor Thomas M. Menino is seeking a change in state law that would allow the School Department to extend the school day, shake up teaching staffs, and make other changes with less interference from the city’s teachers’ union. He has proposed spending millions of additional dollars.

Menino, who appoints the School Committee, has been pushing for overhauling the student assignment system and set up the advisory committee to vet potential changes. The mayor hopes a new system will allow more children from the same neighborhood to attend the same school.

Under the current system, students on the same street often head off each morning to schools many miles apart. That is because the city is divided into three massive student assignment zones, each offering families a choice of about two dozen schools.

The four proposals under consideration would, for the most part, greatly reduce the number of choices as well as the average distance from home to school — from nearly 2 miles to a little more than a mile.

The closer proximity has sparked a lively debate on the advisory committee about whether students who live in a school’s so-called “walk zone” — within about a mile of a school — should still have a priority in school assignments.

The advisory committee is expected to make a recommendation on the walk zone Monday night in addition to endorsing one of the student assignment proposals.

The advisory committee appears to be largely split among two proposals developed by a professor and doctoral student at MIT and specialists from other institutions. Those two proposals are somewhat similar and each would represent the most dramatic change from the current system.

The two proposals would do away with the standard practice of drawing student assignment boundaries on a map. Instead, a complex algorithm would generate a list of schools from which parents can choose based on a variety of factors, such as distance from home, school capacity, and MCAS performance.

One proposal would offer students as few as seven school choices and as many as 18 choices, depending on the area of the city. The other would offer nine to 23 choices.

Some advisory committee members are leaning toward the two more traditional proposals, which would divide the city into 10 or 11 assignment zones. The 10-zone plan would offer three to 14 choices, depending on the zone. Choices under the 11-zone plan would range between three and nine.

The 10-zone plan had been removed from consideration earlier this month, but was revived last week.

Interest in the MIT proposals extends beyond the advisory committee.

The two proposals by the MIT academics won a ringing endorsement last week from the Metropolitan Area Planning Council, after it researched all the proposals.

“It’s the most balanced approach,” said Marc Draisen, the council’s executive director. “It doesn’t focus just on proximity. It takes into account equitable access to quality schools.”

Quest, a grass-roots parents’ group, also released a position paper last week saying that the MIT proposals hold the greatest promise of ensuring that all children have access to quality schools.

But the group decided against endorsing those proposals or any of the other ones. Among their concerns: The city has a dearth of quality schools and has failed to develop an adequate way of measuring school quality.

“How you assign seats doesn’t matter if there are not enough quality seats for everyone,” said Sai Samant, a Jamaica Plain mother and Quest member. “It’s a tough problem.”